Typically, computer and data storage equipment is housed in standardized equipment enclosures. These equipment enclosures normally comprise an outer, aesthetically pleasing housing which is supported by an inner rack. The rack usually comprises a substantially rectilinear metal frame including several vertical columns each provided with a plurality of mounting and alignment holes which permit the mounting of various equipment hardware to the rack. The individual components mounted inside the equipment enclosure typically are supported by support rails that mount to the columns of the rack. The components supported by the rails normally are supplied with power by power distribution units that mount to the rear columns of the rack. The power distribution units comprise a plurality of electrical receptacles to which the electrical plugs of the various components can be coupled.
Recently, there have been increased efforts in the industry to maximize equipment packing density within equipment enclosures. These efforts have resulted in an increased number of components that require current being housed within the equipment enclosures. Conventional power distribution units do not have the current carrying capacity needed to satisfy the demands of these new systems. Notably, this deficiency often cannot be remedied by the use of additional known distribution units due to the limited rear column space of the equipment enclosures and the limited space between the rear columns and the outer enclosure housing.
In addition to these current capacity problems, conventional power distribution units also create usability problems. In particular, conventional power distribution units impede online field replacement of component modules such that inoperative or malfunctioning modules cannot be quickly removed from the rear of the enclosure without shutting the system down. Specifically, known power distribution units encroach upon the horizontal equipment envelope of the enclosure, physically inhibiting module removal. To replace these modules in such systems, the entire power distribution unit must be removed from the rack, creating risks of electrical plug disconnection and even electrical shock to the technician.
Another usability problem associated with conventional power distribution units concerns cable management. As identified above, typical power distribution units have relatively low current carrying capacity. This means that several such power distribution units are necessary to supply the current needed to operate the many components contained within the equipment enclosure. Even in situations in which several such power distribution units fit within the enclosure, cable management is difficult in that several power cords must be routed from the equipment components to the several power distribution units within the enclosure as well as from the power distribution units to the current source of the room in which the enclosure is located. In addition to creating confusing tangles of power cords within the enclosure, such arrangements create current supply problems where the number of current outlets in the room are limited.
From the above, it can be appreciated that it would be desirable to have a power distribution unit which avoids the above-identified problems.